Pivot suspension for ribbon-like louver

ABSTRACT

A pivot suspension for a ribbon-like louver, particularly for an array of louvers used in a controllable solar screen, in which the bearing surface of each pivot suspension intersects the turning axis of the respective louver to reduce friction, and a resilient portion of the suspension loops around the bearing surface back to the axis to hold the louver in tension.

United States Patent [191 Streeter, Jr.

[451 July 3,1973

[ PIVOT SUSPENSION FOR RIBBON-LIKE LOUVER [76] Inventor: Edward C. Streeter, Jr., 128 Heck Avenue, Ocean Grove, NJ. 07756 [22] Filed: Aug. 22, 1971 [21] App]. No.: 173,804

[52] U.S. Cl 49/74, 160/166, 160/176 [51] Int. Cl E06!) 7/08 [58] Field of Search 160/107, 328, 166,

[56] References Cited UNITED STATES PATENTS 2,520,272 8/1950 Bopp et a1. 160/166 A 3,524,281 8/1970 Streeter 49/74 Primary ExaminerKenneth Downey Attorney-James A. Eisenman et a1.

[57] ABSTRACT A pivot suspension for a ribbon-like louver, particularly for an array of louvers used in a controllable solar screen, in which the bearing surface of each pivot suspension intersects the turning axis of the respective louver to reduce friction, and a resilient portion of the suspension loops around the bearing surface back to the axis to hold the louver in tension.

4 Claims, 6 Drawing Figures PATENTEDJUL 3 ma SHEEI 2 0F 2 INVENTOR. Edward C. Streeter,Jr. BY

ATTORNfYJ' PIVOT SUSPENSION FOR RIBBON-LIKE LOUVER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention concerns suspensions for parallel ribbon-like louvers of adjustable screens, and it is particularly applicable to remotely controlled electromagnetically operated environmental screens suitable for permanent hermetic sealing in the air space of dual glazed insulating windows and skylights.

The pivot suspensions of the present invention permit a refinement and simplification of the floating ribbon environmental screen disclosed in U.S. Pat. No. 3,524,28 l granted Aug. 18, 1970. The prior screen has a separate motor rotor attached to an end of each louver and permanently magnetized perpendicularly to the rotational axis of the louver. Frictionless torsional suspensions support the rotors for limited rotation of the louvers, and a common control coil adjacent the rotors produces a magnetic control field perpendicular to the common plane of the rotational axes to exert a control torque on the rotors.

In the bistable form of the screen, magnetic induction in a strip of steel parallel to the common plane of the rotational axes and suitably spaced from the rotors produces a locking torque on each permanent magnet rotor sufficient to hold the end of the louver in one or the other of two attitudes of stable equilibrium. The

' louvers remain in one attitude of respose without consumption of power until a momentary control torque opposes and exceeds the locking torque. The transient control field overpowers the locking torques and transfers the ends of the louvers to the other attitude of repose.

The two stable attitudes of the ends of the louvers are determined solely by mechanical limit stops and are thus independent of the torques produced by the louver suspensions. Accordingly, a frictionless louver suspension is not essential, and rotation of a louver may be opposed by appreciable friction.

2. Description of the Prior Art A known means for supporting an adjustable ribbonlike louver comprises a slender shaft attached to an end of the louver and provided with a collar or enlarged head that rests on an annular shoulder or lip of a bushing fixed to the screen frame. However, the expense of the mating parts and the awkwardness of assembly discourage the substitution of this suspension for the frictionless torsional suspension. Furthermore, the frictional torque of this annular type of suspension is undesirably large, inherently exceeding that of a flat pivot, which has a circular rubbing surface concentric with the axis of rotation. Quantitatively, the frictional torque of a collar bearing having an inner radius r and an outer radius R kr is k l/k 1 times the frictional torque of a'flat pivot of radius r. The practical superiority of a flat pivot increases as the radius r of the shaft decreases, that is, as the shaft is reduced to a fine wire.

SUMMARY OF THE INVENTION The present invention takes advantage of the limited rotation of the louvers to provide a suspension assembly comprised of a plurality of suspension elements for louvers, each element having a pivot and recess connection with a common support member. The new suspension element comprises a fine wire of circular cross section having a pivot pin portion on the louver axis that is connected to a coaxial louver coupling portion by a resilient offset loop portion. The pivot pin portion substantially closes the loop, leaving a free opening that is less than the effective thickness of the common sup port member. Accordingly, the loop can be momentarily expanded slightly to permit the pivot pin to be slipped into the respective recess where it is resiliently maintained against radial displacement upon releasing the loop. When a louver is attached to the coupling portion, the louver tension expands the loop sufficiently to provide adequate clearance of the suspension element from the louver side of the support member.

The new suspension element typically provides a flat pivot because it is convenient to cut off contiuous wire stock in the forming machine perpendicularly to its length, thereby producing a flat end for the pivot pin portion. The frictional torque is moderate because the radius of the wire is just sufficient to limit the stress in the loop caused by the louver tension. Spring-tempered beryllium-copper alloy is a suitable material for the suspension element because it is non-magnetic, it has excellent spring characteristics, and it bears well against the common support member, which is made of coldrolled steel.

The frictional torque of the new suspension element can be further reduced by forming a bearing surface generated by a line extending from and revolving about the louver axis of rotation, for example, a rounded or conically pointed surface. This reduction is unimportant in a bistable screen where power is consumed only momentarily, but sufficiently low friction is attainable to make practical the magnetically centered mode of screen operation described in the above-mentioned U.S. Pat. No. 3,524,281. In this operating mode, magnetic coupling between adjacent permanent magnet rotors produces a restoring torque tending to align the magnetic axes of the rotors in the common plane of the rotational axes. The locking torque on each rotor is arranged to be negligible.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a greatly enlarged view of the new suspension element looking perpendicularly to its plane of symmetry;

FIG. 2 is a cross-sectional view, on an enlarged scale, of a typical beam of an electromagnetically operated environmental screen employing the pivot suspension of the present invention to support ribbon-like louvers;

FIG. 3 is a view of the beam of FIG. 2 parallel to the louver axes of rotation with portions broken away to reveal internal construction;

FIG. 4 is a view of the side of the beam of FIG. 2 with portions broken away to reveal internal construction and with the louver rotated FIG. 5 is a view of the beam cover; and

FIG. 6 is a view, on the same scale as FIG. 1, of a rotor-louver connector looking perpendicularly to its plane of symmetry.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT A typical suspension element 11, shown greatly enlarged in FIG. 1, comprises a wire part of circular crosssection with a straight shank 12 having a longitudinal axis 13. A circular eye 14, centered on the axis 13, extends from one end of the shank 12 and nearly closes upon itself, leaving a gap 15 that is less than the diameter of the wire. The wire projects substantially perpendicularly from the other end of the shank 12, follows approximately a semicircular path away from the eye 14, and returns almost to the axis 13, forming a U- shaped loop 16 opening toward the axis 13 with slightly convergent sides. A pivot pin portion 17 extends from the free end of the loop to the adjacent end of the shank 12, substantially closing the loop 16 and leaving an opening 18 that is less than the diameter of the wire. The narrowness of the gap 15 and the opening 18 reduces the chance of tangling the suspension elements during production. All portions of the suspension element 11 lie in a common plane.

A flat end 19 is left on the pivot pin portion 17 to provide a circular bearing surface. The loop 16 is resilient and expands slightly when a tension equal to the desired louver tension is applied between the eye 14 and the end 19 of the wire. This tension causes the pivot pin portion 17 to align coaxially with the shank 12 and increases the opening 18 appreciably.

The new suspension assembly, comprising a plurality of suspension elements 11 and a common support member, is shown in FIGS. 2-4, which illustrate a typical beam of an electromagnetically operated environmental screen having ribbon-like louvers. A beam shell 21, seen most clearly in FIG. 2, is a channel of sheet steel having a U-shaped rectangular cross'section and comprises a back 22 on the edge of the screen between a side 23 facing indoors and a side 24 facing outdoors. The free edges of the sides 23 and 24 are doubled back toward the interior of the shell 21 to provide narrow lips 25 and 26, respectively, parallel to and slightly spaced from the adjacent sides.

A stator housing channel 27 of sheet steel is contained within the beam shell 21. The channel 27 comprises a web 28, which lies against the side 24, a flange 29 that extends between the sides 23 and 24 and serves as a beam cover, and a flange 31 that is parallel to the back 22 and serves as a common support member for the suspension elements 11.

Truncated conical recesses 32 are formed in the exterior face of the flange 31 to support the pivot pin ends 19 of the suspension elements 11 on the louver axes of rotation. The recesses 32 are revealed as dimples 33 on the interior face of the flange 31. Each recess 32 is located at the center of a semicircular prominence 34 that projects from the cantilevered edge of the flange 31 and that is bounded by a pair of semicircular notches 35 in the edge. The radius of the prominence 34 is sufficiently short relative to the loop 16 to provide adequate clearance for the suspension element 11, which can be rotated through slightly more than a straight angle unless otherwise restrained. The thickness of the flange 31 is greater than the opening 18 in the unstressed suspension element 11; consequently the pivot pin portion 17 remains in the recess 32 once it has been forced into this position.

The stator housing channel 27 is retained within the beam shell 21 by the lips 25 and 26, which bear against the exterior face of the flange 29. The sides 23 and 24 of the beam shell are prevented from spreading apart by a plurality of equally spaced tabs 36 lanced from the flange 29 adjacent the web 28 and by a narrow lip 37 extending along the free end of the flange 29. The tabs 36 and the lip 37 project perpendicularly from the exterior face of the flange 29 into the spaces between the lips 26 and 25, respectively, and the adjacent sides 24 and 23, respectively.

Each suspension element 11 supports a rotor-louver connector 38 on which a permanent magnet rotor 39 is mounted and to which an end of a louver 41 is attached for limited rotation about the axis 13.

The permanent magnet rotor 39 has a cylindrical disk shape with the axis of symmetry coaxial with the axis 13. The rotor 39 is provided with a round axial hole 42 and is made of low cost sintered Alnico ll material. The rotor is magnetized across its diameter, and the magnetic axis is indicated in FIG. 4 by a dashed line 43 at a 45-degree angle to the common plane of the suspension element 11 and the louver 41.

The rotor-louver connector 38, shown separately in FIG. 6 on the same greatly enlarged scale as that of FIG. 1, is a narrow strip of non-magnetic flat spring ma terial with a rotor clip 44 at one end of a straight shank 46 having a longitudinal axis 13'. A louver hook 47 and an axial movement limiting stop 48 are formed at the opposite end of the shank 46. The rotor clip 44 has a leg 49 that extends from the shank 46 parallel to the axis 13' but slightly offset therefrom. A return bend 51 centered on the axis 13' joins the leg 49 to a corresponding leg 52 on the opposite side of the axis 13'. The bend 51 is slightly less than semicircular; consequently the leg 52 diverges somewhat from parallelism with the leg 49 in the absence of forces tending to pinch the legs together. A short ear 53 projects perpendicularly outward from the free end of the leg 52. The louver hook 47 comprises an offset portion 54, a throat portion 55 extending parallel to the axis 13' but slightly displaced therefrom, and a recurving portion 56 centered on the axis 13'. The stop 48 extends from a fold at the tip of the recurving portion 56 and follows the concave side of the hook 47 back to the offset portion 54 from whence it projects perpendicularly across the axis 13' to provide a resiliently outstanding arm 57.

The permanent magnet rotor 39 is mounted on the rotor-louver connector 38 by pushing the rotor clip 44 through the rotor hole 42 until stopped by the ear 53. The legs 49 and 52 bear firmly against the cylindrical wall of the hole 42 and resist any tendency of the rotor to turn relative to the shank 46. The return bend 51 projects beyond the rotor 39 and serves as a loop for coupling with the eye 14 of the suspension element 1 1.

The shank 46 of each rotor-louver connector 38 extends through a round hole 58 in the flange 29 centered on the louver axis of rotation and exposes the louver hook 47 and the stop 48 to the exterior of the beam shell. The length of the arm 57 exceeds the diameter of the hole 58; consequently it bends toward the shank 46 as it is pushed through the hole. Thereafter, the arm 57 limits axial movement of the rotor-louver connector 38 toward the interior of the stator housing channel 27 and thus maintains adequate spacing between adjacent rotors 39 before the louvers 41 are attached to the hooks 47.

Each louver 41 is made of a corrugated ribbon of spring tempered high strength aluminum foil that is slightly wider than the spacing between adjacent rotational axes 13 in order that adjacent louvers overlap in the closed position. An eyelet 59 is provided at the end of the louver centered on its longitudinal axis for engaging the hook 47. The axes of the louver corrugations extend parallel to the width of the louver to stiffen the louver transversely and to render it longitudinally resilient. An analysis of this type of louver is contained in U.S. Pat. No. 3,342,244, granted Sept. 19, 1967.

A louver opening limit stop 61 is provided for each louver 41 in the form of a rectangular tab lanced from the flange 29 adjacent the-lip 37. The plane of the stop 61 is substantially parallel to the plane of the louver in its fully open position, and it contacts the face of the louver near its edge.

The attitude of the louvers 41 is changed by means of a remotely energized common control coil 62, 62' that creates a laminar magnetic control field perpendicular to the common plane of the louver rotational axes to exert a control torque on the rotors 39. The coil 62, 62' is contained in aluminum coil supporting channels 63 and 64, which occupy the inside corners of the stator channel 27 adjacent the web 28 and the flanges 31 and 29, respectively. The channels 63 and 64 lie in back to back relationship with their interiors facing the flanges 31 and 29, respectively, and are held apart by a sheet steel magnetic pole channel 65. Inwardly directed dimples 66 and 67 in the flanges 29 and 31, respectively, limit movement of the channels 63 and 64, respectively, away from the web 28. The parallel portions of the coil 62, 62' are joined by return bends (not shown) in the corners of the screen. The coil 62, 62 is wound .with multiple turns of an insulated electrical conductor, which is preferably aluminum wire or foil to reduce weight and to minimize movement relative to the supporting channels 63 and 64 in response to temperature changes.

The magnetic pole channel 65 is spaced opposite the line of rotors 39 at a distance suitable for developing the desired amplitude of locking torque. The exterior of the channel 65 is shown facing the rotors to produce sufficient locking torque for bistable screen operation. The interior of the channel 65 is positioned to face the rotors 39 when magnetically centered screen operation is desired, thus minimizing locking torque. As previously discussed, the suspension elements are conically pointed to reduce friction in this operating mode.

It is to be understood that the use of the pivot suspen sion is not limited to electromagnetically operated screens. For example, the permanent magnet rotors 39,

the coil 62, 62' andthe magnetic pole channel 65 can be omitted if the louvers are turned by an electric field in accordance with the teachings of U.S. Pat. No. 3,210,809, granted Oct. 12, 1965.

I claim:

1. A suspension assembly for an adjustable screen wherein a plurality of ribbon-like louvers are held under tension for limited turning about parallel transversely spaced longitudinal axes of rotation, comprising a louver support member intersecting said axes, a plurality of suspension elements for said louvers, each suspension element having an outer end pivotally engaging said support member, an inner end coupled to a respective louver, and a resilient loop portion joining the ends and extending radially and axially around said support member.

2. A suspension assembly according to claim 1 wherein each suspension element is pivotally suspended by a terminal pivot and recess connection with said support member, and the unstressed loop leaves an opening that is less than the effective thickness of the louver support member, whereby the suspension element is resiliently maintained against radial displacement at the pivot and recess connection.

3. A suspension assembly according to claim 1 wherein each suspension element is a wire pivotally suspended on its outer end in a respective recess in the louver support member, said end having a bearing surface intersecting the louver axis of rotation.

4. A suspension assembly according to claim 1, including a coupling eye on the inner end of each suspension element, and a magnetic rotor for each louver, and wherein each suspension element is coupled to a respective louver by a louver connector comprising a non-magnetic flat strip spring member having a spring clip to loop the eye and to pass through the rotor to be compressed thereby in mounting attachment, a shank portion on the louver connector substantially coaxial with the turning axis of the louver, an offset louver hook at the end of the shank, and a resilient stop arm extending transversely from the shank adjacent the junction with the offset louver hook. 

1. A suspension assembly for an adjustable screen wherein a plurality of ribbon-like louvers are held under tension for limited turning about parallel transversely spaced longitudinal axes of rotation, comprising a louver support member intersecting said axes, a plurality of suspension elements for said louvers, each suspension element having an outer end pivotally engaging said support member, an inner end coupled to a respective louver, and a resilient loop portion joining the ends and extending radially and axially around said support member.
 2. A suspension assembly according to claim 1 wherein each suspension element is pivotally suspended by a terminal pivot and recess connection with said support member, and the unstressed loop leaves an opening that is less than the effective thickness of the louver support member, whereby the suspension element is resiliently maintained against radial displacement at the pivot and recess connection.
 3. A suspension assembly according to claim 1 wherein each suspension element is a wire pivotally suspended on its outer end in a respective recess in the louver support member, said end having a bearing surface intersecting the louver axis of rotation.
 4. A suspension assembly according to claim 1, including a coupling eye on the inner end of each suspension element, and a magnetic rotor for each louver, and wherein each suspension element is coupled to a respective louver by a louver connector comprising a non-magnetic flat strip spring member having a spring clip to loop the eye and to pass through the rotor to be compressed thereby in mounting attachment, a shank portion on the louver connector substantially coaxial with the turning axis of the louver, an offset louver hook at the end of the shank, and a resilient stop arm extending transversely from the shank adjacent the junction with the offset louver hook. 